Below is a chart of the 50-day rolling correlation (using daily %
change) between the metal and the currency going back to 1975. As
shown, there has just been a big spike in correlation that is
very rarely seen. The 50-day correlation, which is currently at
0.33, has only been above the 0.30 level 1.2% of the time since
1975.

We're not sure if there are any believers in the 'strong'
form of efficient markets left these days, but if so, let them
explain this nonsense:

We're guessing they are using the Dollar Index to represent the
dollar. This obviously can't go on forever and this has to be
setting up a riskless arbitrage somewhere. Perhaps sell gold for
US dollars, use the dollars to buy another currency, and then buy
the same quantity of gold that you initially sold with your new
currency. The euro and yen probably wouldn't work since they are
too closely watched, a back of the envelope shows gold in euro
and yen close to gold in dollars, though perhaps a fast trading
system could catch arbitrages when they deviate. But perhaps a
less followed currency would workd. Some gold price, in some
currency, has to be going out of whack for both gold and the
dollar to rise as shown above.